CN111619188B

CN111619188B - Method of making shaped composite laminate stiffeners

Info

Publication number: CN111619188B
Application number: CN202010490777.6A
Authority: CN
Inventors: 克里斯托弗·戴维·奥芬森德; 柯克·本·卡伊塔; 基兰·P·戴维斯; 马修·R·索亚
Original assignee: Boeing Co
Current assignee: Boeing Co
Priority date: 2015-10-06
Filing date: 2016-09-28
Publication date: 2022-02-08
Anticipated expiration: 2036-09-28
Also published as: ES2760944T3; PT3162544T; CN111619188A; RU2727627C2; CN106985488A; EP3162544B1; RU2016129734A; CN106985488B; US20170095983A1; US10399283B2; EP3162544A1

Abstract

The present invention provides a method of manufacturing a profiled composite laminate reinforcement by assembling a substantially planar composite laminate charge and forming the charge into a substantially straight reinforcement having a desired cross-sectional shape. A profile is formed in a stiffener having an inboard radius and an outboard radius. Ply wrinkling is substantially eliminated by reducing the compressive strain on the inboard radius as the stiffener is formed.

Description

Method of making shaped composite laminate stiffeners

This application is a divisional application of the invention patent application entitled "method of making a profiled composite laminate reinforcement" filed on 28/9/2016, chinese application No. 201610861728.2, the entire contents of which are incorporated herein by reference.

Technical Field

The present disclosure relates generally to composite laminate stiffener fabrication and, more particularly, to a method and apparatus for fabricating a profiled stiffener (ply) that reduces ply wrinkling.

Background

Profiled composite laminate stiffeners, such as concave stringers, may be manufactured using a combination of primary and secondary forming operations. For example, press forming may be used to form a flat composite charge into a straight reinforcement having a desired cross-sectional shape (e.g., without limitation, a hat-shaped cross-section). In the secondary forming operation, a substantially straight semi-flexible compactor having a hat-shaped cross-section is used to form the stringer onto the curved forming tool along its length. Atmospheric pressure, and optionally autoclave pressure, applied to the compactor through the vacuum bag, forms the stiffeners onto the curved forming tool, imparting the desired curvature to the stiffeners. During the secondary forming operation, bending strains are created in the stiffener as it conforms to the profile of the forming tool. This bending strain can cause local buckling of the composite fibers in the green laminate, creating undesirable wrinkles in the cured portions, particularly in the area near the inside radius of the profiled stiffener.

Accordingly, there is a need for a method and apparatus for reducing laminate wrinkling during the formation of composite laminate reinforcements by controlling in-plane strain in those areas of the laminate that may experience warpage.

Disclosure of Invention

The disclosed embodiments provide a method and apparatus for manufacturing a profiled composite laminate reinforcement that reduces or eliminates ply wrinkling caused by compressive strain induced in the laminate as it is profiled. By reducing or substantially eliminating ply wrinkling, the structural performance of the stiffener may be improved, and repair, rework, inspection, and certification costs may be reduced.

In one embodiment, ply wrinkling is reduced or eliminated by increasing the stretch on the outside radius of the compactor used to form the laminate onto the forming tool surface. The tensile strain on the outside radius of the compactor is increased by cutting a slot in the outside radius of the compactor. The slots allow the laminate to be sealed to the compactor and allow out-of-plane movement of the laminate without introducing compressive strain into the inside radius of the stiffener. The suppression of compressive strain along the inside radius is achieved by maintaining tension on the outside radius of the laminate as it is formed onto the form curing tool. A slot in the outer radius of the compactor allows the compactor to be deployed along the outer radius, thereby imparting tension to the outer radius. The tensile strain achieved on the outside radius counteracts the compressive strain created on the inside radius when the stiffener is formed onto the forming surface of the curing tool.

In another embodiment, compressive strain on the inside radius of the forming stiffener is reduced or eliminated by using a forming compactor having a curvature greater than the curvature of the forming tool surface on which the stiffener is formed. A curved compactor increases the tension applied to the inside radius of the compactor. The resulting tensile strain at the inside radius of the stiffener when the stiffener is conformed to the tool surface counteracts the compressive strain on the inside radius of the stiffener created by the forming process. The tensile strain applied to the stiffener is maintained throughout the contouring process and continues throughout the curing of the stiffener.

In accordance with one disclosed embodiment, a method for manufacturing a profiled composite laminate stiffener is provided. The method includes assembling a substantially planar composite laminate charge, forming the composite laminate charge into a substantially planar stiffener having a desired cross-sectional shape, and forming a profile in the stiffener having an inside radius and an outside radius. The method also includes reducing the compressive strain on the medial radius during shaping of the profile. Assembling the composite laminate charge includes laying up prepreg ply sections each having a 0 ° fiber orientation. The lay-up prepreg ply sections comprise overlapping ply sections. Forming the contour in the reinforcement includes placing a straight reinforcement on the curved tool surface, placing a compactor on the straight reinforcement, and compacting the reinforcement onto the curved tool surface using the compactor. Reducing the compressive strain on the inboard radius includes increasing the tensile strain on the outboard radius of the compactor. Increasing the tensile strain on the outside radius of the compactor is performed by forming a series of slits in the outside radius of the compactor. Reducing the compressive strain on the inside radius of the composite laminate stiffener is performed by applying tension to the outer end of the composite laminate stiffener using a compactor.

In accordance with another disclosed embodiment, a method for manufacturing a shaped composite laminate hat stiffener is provided. The method includes forming a substantially flat composite laminate charge into a substantially straight reinforcement having a hat-shaped cross-section, forming a contour in the reinforcement using a compactor, and allowing the compactor to extend when the compactor forms the contour in the reinforcement. The profile has an inboard radius and an outboard radius, and forming the profile with the compactor includes compacting the stiffener against a tool having a curved tool surface that substantially matches the inboard radius. The method also includes reducing out-of-plane buckling of the stiffener in the region of the inboard radius of the stiffener by creating a tensile strain at the outboard radius that reduces a compressive strain in the region of the inboard radius of the stiffener. Creating tensile strain includes forming a series of slits in the compactor that allow an inside radius of the compactor to extend as the compactor forms the stiffener onto the curved implement surface. In one variation, creating the tensile strain includes applying tension to an inside radius of the stiffener. Applying tension to the inside radius of the stiffener includes applying tension using a compactor, wherein the compactor is shaped and has a curvature greater than a curvature of the curved tool surface. The method further includes curing the reinforcement, wherein the tensile strain continues to be created throughout the curing of the reinforcement.

In accordance with yet another disclosed embodiment, an apparatus for forming a shaped composite laminate reinforcement is provided. The apparatus includes a compactor adapted to form a composite laminate reinforcement and to be pressed against the tool surface, the compactor having a curvature greater than a curvature of the tool surface. The compactor is extendable and configured to apply tension to the reinforcement as it is formed on the tool surface. The compactor has a hat-shaped cross-section including a cover portion, a pair of flange portions, and a pair of web portions connecting the cover portion and the flange portions. The cover portion includes a series of spaced apart slits therein. The compactor also includes an inboard radius segment and an outboard radius segment, and the inboard radius segment includes a series of slits therein to allow the compactor to flex.

In accordance with another disclosed embodiment, an apparatus for forming a profiled composite laminate stiffener having a hat-shaped cross-section is provided. The apparatus includes a compactor adapted to form a composite laminate reinforcement onto a curved tool surface. The compactor includes a cover portion, a pair of flange portions, and a pair of web portions connecting the cover portion and the flange portions. The compactor further includes a series of spaced apart slits therein extending through the flange portion and at least partially into the web portion for imparting tensile strain to the composite laminate stiffener as it is formed onto the curved tool surface. The apparatus may also include a pad adapted to cover and transfer the forming force to the flange portion. The pad may be formed of a substantially flexible material. The caul plate may also include a plurality of slits therein that allow the caul plate to flex and conform to the flange portions as the compactor forms the composite laminate reinforcement onto the curved tool surface.

The features, functions, and advantages can be achieved independently in various embodiments of the present disclosure or may be combined in yet other embodiments, further details of which can be seen with reference to the following detailed description and drawings.

Drawings

The novel features believed characteristic of the illustrative embodiments are set forth in the appended claims. The exemplary embodiments, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an exemplary embodiment of the present disclosure when read in conjunction with the accompanying drawings, wherein:

fig. 1 is an illustration of a perspective view of a profiled hat stringer.

Fig. 2 is an illustration showing a perspective view of converting a flat composite laminate charge into a straight stringer having a hat-shaped cross-section.

FIG. 3 is a diagram illustrating a longitudinal side view of a tool assembly employing one embodiment of a compactor.

FIG. 4 is a view similar to FIG. 3 but showing the compactor and stringer assembled and formed down onto the forming tool, with the vacuum bag not shown for clarity.

FIG. 5 is an illustration of a cross-sectional view taken along line 5-5 in FIG. 4, but also showing the caul plate and vacuum bag.

Fig. 6 is an illustration of a perspective view of the compactor shown in fig. 3, 4, and 5 after it has conformed to the curvature of the forming tool.

FIG. 7 is an illustration of a plan view of an alternative compactor plate forming part of the tool assembly shown in FIG. 5.

FIG. 8 is a diagrammatic side elevational view of the compactor shown in FIG. 7 illustrating a reduction in compressive strain along an inside radius of the compactor.

Figure 9 is an illustration of a profiled stringer to illustrate the reduction of wrinkles in the inside radius region of the stringer.

FIG. 10 is an illustration of a longitudinal side view of an alternative embodiment of a compactor and forming tool having a plurality of contoured and flat tool surfaces.

Fig. 11 and 12 are illustrations of side views of two adjacent segments of a discontinuous 0 ° ply.

FIG. 13 is a diagrammatic view of a forming tool assembly employing an alternative embodiment of a compactor.

FIG. 14 is an illustration of the forming tool assembly illustrated in FIG. 13 with the compactor partially drawn down onto the forming tool.

Fig. 15 is an illustration of the area labeled "fig. 15" in fig. 14, but with a portion of the forming tool broken away to better illustrate the tensile strain in the cover of the stringer.

Fig. 16 is an illustration of a flow chart of a method of making a corrugated reduced profile composite laminate reinforcement.

FIG. 17 is an illustration of a flow chart of a method of manufacturing a shaped composite laminate hat stiffener.

FIG. 18 is an illustration of a flow chart of an aircraft manufacturing and service method.

Fig. 19 is an illustration of a block diagram of an aircraft.

Detailed Description

Referring initially to fig. 1, the disclosed embodiments provide a method and apparatus for manufacturing a profiled composite laminate reinforcement 20 having a curvature 30 along its long axis 32. In the illustrated example, the stiffener 20 is a hat stringer having a hat cross-section 22, however, the principles of the disclosed embodiments may be applied to a variety of different elongated stiffeners having any of a variety of cross-sectional shapes, including but not limited to C, J, Z and T cross-sectional shapes.

The hat section 22 includes a cover 24 connected to a pair of outwardly turned flanges 26 by a pair of webs 28. The illustrated stiffener 20 is concave in shape with the cap 24 positioned along an inside radius 34 of the curvature 30 and the flange 26 positioned along an outside radius 36. As used herein in connection with forming the stiffener 20, "inboard radius" and "outboard radius" refer to the inboard and outboard sections of the stiffener 20, respectively, or in other words, those composite plies located near the inboard radius 34 and those plies located near the outboard radius 36 of the stiffener 20. In some embodiments, the cover 24 may be positioned along the outside radius 36 while the flange 26 is positioned along the inside radius 34. In still other embodiments, the stiffener 20 may have more than one curvature 30 along its length and straight sections.

In one embodiment, the profiled stiffener 20 shown in FIG. 1 may be manufactured using primary and secondary forming operations. Fig. 2 illustrates a primary forming operation in which a flat composite laminate charge 38 is assembled and stamped to form a straight stiffener 42 having a hat-shaped cross-section. However, other processes may be employed to form the charge 38 into a straight reinforcement 42 having a desired cross-sectional shape. The charge 38 includes a stack of prepreg plies 40, including 0 ° plies 40a, having various fiber orientations arranged according to a predetermined ply plan suitable for the application. As will be discussed below, some or all of the 0 degree plies 40a may optionally be discontinuous, for example in the form of ply segments 70, to aid in the subsequent shaping of the straight stiffeners 42.

Attention is now directed to fig. 3-6, which illustrate a compactor 44 and forming tool 46 that may be used in a secondary forming operation to form a straight stiffener 42 (fig. 2) into a desired profile, such as the concave shape shown in fig. 1. The forming tool 46, which may include a curing tool in which the stiffener 20 is cured, has a curved tool surface 48 formed to substantially match the desired curvature 30 (fig. 1) of the stiffener 20. The compactor 44 is used to form the stiffener 42 down onto the tool surface 48, and, as will be discussed in more detail later, is configured to avoid introducing high levels of compressive strain along the inside radius 34 of the stiffener 20 (i.e., the cover 24), which may result in undesirable ply wrinkling. Compactor 44 has a cross-sectional shape that substantially matches the hat-shaped cross-section of stiffener 20. The compactor includes a cover portion 50 connected to a pair of flange portions 52 by a pair of web portions 54. Compactor 44 may be formed from any suitable material (e.g., without limitation, a composite material) having sufficient strength and stability to apply compaction pressure to green stiffener 42 in response to an applied forming force F.

The compactor 44 includes a series of longitudinally spaced slits 56 therein that extend completely through each of the flange portions 52 and partially into the web portion 54. During the forming operation, the applied forming force F bends the compactor 44 and stiffener 42 onto the tool 46 such that they assume the shape of the tool surface 48. When a straight compactor 44 is bent onto a curved tool surface 48, the outer radius 65 of the compactor 44 is in tension such that it undergoes axial extension (referred to as tensile strain), while the inner radius 55 is in compression and undergoes axial compression (referred to as compressive strain). The slits 56 in the flange portion 52 open up when stretched during the forming process. The expansion of the slits 56 results in an increase in elongation or tensile strain at the outside radius 65. The increased tensile strain at the outside radius 65 (flange portion 52) counteracts and thus reduces the compressive strain in the compactor cover portion 50. The increase in tensile strain in the flange portion 52 of the compactor 44 is transferred to the flange 26 of the green stiffener 42, which in turn reduces the compressive strain in the stiffener cover 24 and the accompanying ply wrinkling.

With particular reference to figures 4 and 5, in use, a straight stiffener 42 is placed on the tool surface 48 and the now substantially straight compactor 44 is placed into the straight stiffener 42. Alternatively, depending on the application, a shim plate 58 (FIG. 5) is placed on top of the compactor 44 in face-to-face contact with the flange portion 52 of the compactor 44. A vacuum bag 62 (fig. 5) is then placed over the assembly of forming tool 46, stiffeners 42, compactor 44, and caul plate 58. Vacuum bag 62 is sealed around forming tool 46 and then vented so that atmospheric pressure applies a forming force F to compactor 44. The applied forming force F is transferred from the compactor 44 to the stiffener 42 such that the stiffener 42 forms down onto the tool surface 48. Although not shown in the figures, the stiffener forming process may be performed within an autoclave (where the internal autoclave pressure may include a portion of the forming force F).

As the forming force F is applied, the compactor 44 bends to conform to the curved tool surface 48. The slits 56 along the outside radius 65 (see FIG. 6) of the compactor 44 are spread during this bending, allowing the compactor 44 to flex and elongate as it conforms along its length to the curvature of the tool surface 48. As previously mentioned, the slits 56 function to increase the tensile strain along the outside radius 65 of the compactor 44, as they allow the outside radius 65 to elongate much more in response to the tensile stress at the outside radius 65 caused by the applied shaping force F that would otherwise elongate. Due to the increased tensile strain at the outside radius 65, the tension created by the bending stress is transferred or redirected inward within the stiffener 42 and is applied at a region within the stiffener 41 that is closer to the inside radius 55. For example, a portion of the applied stretch may be transferred from the outside radius 65 and applied at an area of the stiffener 42 that is somewhere between the inside radius 55 and the outside radius 65. The tension applied closer to the inboard radius at least partially counteracts the compression experienced by compactor 44 at inboard radius 55, thereby reducing the compressive strain at inboard radius 55.

During the forming operation, the applied forming force F is transferred to the reinforcement 42 by the compactor 44. Due to the forming force F that presses them together and the frictional and/or adhesive forces between them, the compactor 44 and the stiffener 42 are tightly coupled together and do not slide substantially relative to each other. The adhesion between compactor 44 and stiffener 42 results from the tackiness of green stiffener 42, which increases upon heating during forming and/or curing. Depending on the application, and thus the material from which compactor 44 is formed, it may be necessary or desirable to increase the adhesion and/or friction between compactor 44 and stiffener 42 so that the two components do not slip relative to one another during the forming process. The increased adhesion and/or friction may be achieved by treating the surface of compactor 44 such that it exhibits greater friction when contacted by stiffener 42 and/or placing a layer of adhesive (not shown) between compactor 44 and stiffener 42.

An increase in tensile strain that allows compactor 44 to elongate and expand along its length, and a corresponding decrease in compressive strain along inside radius 55, is transmitted from compactor 44 to stiffener 42. The slits 56 also help to achieve a reliable vacuum seal around the green stiffener 42. The shim plate 58 helps to evenly apply the forming force F to the compactor flange portion 52. In one embodiment, the backing plate 58 may be formed of an elastomeric material that allows it to bend and conform to the curvature of the tool surface 48. In other embodiments, as shown in fig. 7, the tie plate 58 may be formed of a more rigid material (such as a composite material) having a series of staggered slots 60 disposed therein to allow the tie plate 58 to flex as desired in response to the applied shaping force F.

Figures 8 and 9 show the profile of the compactor 44 and stiffener 42, respectively, after being forced down onto a curved tool surface 48, and the straight stiffener 42 has assumed the shape of the tool surface 48 (which is formed to complement the shape of the stiffener 42). As the compactor 44 conforms to the curved tool surface 48, the region of the compactor 44 proximate the inside radius 85, and in particular the cover 50, is in compression 66. At the same time, the region of the compactor 44 near the outside radius 95, i.e., the outside sections of the flange portion 52 and web portion 54, is in tension 68, causing the slits 56 to expand and the compactor 44 to deploy. The expansion of the slits 56 in the compactor 44 near the outside radius 65 increases the tensile strain in this region, and this increase in tensile strain counteracts the compressive strain that occurs in the region of the inside radius 55. An increase in tensile strain near outboard radius 65 and a resulting decrease in compressive strain near inboard radius 55 is transferred from compactor 44 to stiffener 42, thereby reducing or eliminating ply wrinkling in cover 24 of stiffener 42. The increase in tensile strain at the outboard radius 35 of the stiffener 42 allows subsequent plies closer to the inboard radius 34 to slide relative to each other, thereby reducing the compressive strain near the inboard radius 34. The stretch 68 and compression 66 experienced by the compactor 44 that is transferred to the inside and

outside radii

34, 35 of the stiffener 42 is maintained throughout the forming process and subsequently throughout curing.

As previously mentioned, in some applications, the stiffener 20 may have more than one curvature 30 along its length and straight sections. For example, referring to FIG. 10, the forming tool 46 may have a plurality of segments 46a-46d with tool surfaces 48 having different profiles that are respectively complementary to corresponding shapes (not shown) of the stiffeners 20. In the example shown, the tool surfaces 48 in

sections

46a and 46d of the tool have an opposite curvature to the curved tool surfaces 48 in section 46 b. The oppositely shaped tool surfaces 48 in

sections

46b and 46d are connected by a substantially straight or flat tool surface 48 in section 46 c. Fig. 10 also shows a compactor 44 adapted to compact a straight stiffener 42 (not shown in fig. 10) against a forming tool 46. The compactor 44 includes two sets of

slits

56a, 56c in the flange portion 52 for reducing compressive strain in the cover 50 when formed over the

sections

46a and 46d of the tool 46, and the compactor 44 includes a third set of slits 56b in the cover 50 for reducing compressive strain in the flange portion 54 when formed over the section 46b of the tool 46. The region of compactor 44 where stiffener 42 is formed on flat tool surface 48 in section 46c does not have any slits 56 therein.

Referring now to fig. 11 and 12, in some embodiments, plies 40a (see fig. 2) having a 0 ° orientation that are generally aligned with the reinforcing fibers with the longitudinal axis 32 (fig. 1) of the strength member 20 may optionally be discontinuous. For example, a 0 ° discontinuous ply 40a may include 0 ° prepreg ply segments 70 (fig. 2, 11, and 12) that are heavy relative to one another along the length of the reinforcement 20. The length L of the deck section 70 will depend on the application and the extent of the stiffener profile. During the profile forming process, in which straight stiffeners 42 are formed down onto the forming tool surface 48, the deck segments 70 are slid 72 relative to each other in-plane (fig. 11) to facilitate forming the inside radius 85 onto the tool surface 48 and to help avoid buckling into out-of-plane wrinkles.

Attention is now directed to fig. 13, 14 and 15, which illustrate an alternative embodiment employing a curved compactor 74 having a radius of curvature 84 that is less than a radius of curvature 88 of the tool surface 48 used to form the straight, green stiffener 42. Thus, the curvature of compactor 74 is greater than the curvature of tool surface 48. Compactor 74 may be formed from any suitable material (such as a composite material) having sufficient stability and rigidity to form green stiffener 42 down onto curved tool surface 48, but which still extends 92 along its length (fig. 13 and 14). Compactor 74 has an inboard radius segment 86 and an outboard radius segment 87. The cross-sectional shape of the compactor 74 is substantially the same as the cross-sectional shape of the straight stiffener 42 and includes a cover portion 76 connected to a pair of flange portions 78 by a pair of web portions 80. In this embodiment, the cover 76 is provided with a series of spaced apart slits 82 in its inner radius section 86, which extend partially into the web 80 of the compactor 74.

Referring now specifically to fig. 14 and 15, in use, green reinforcement 42 is placed on tool 46 and compactor 74 is placed on reinforcement 42. Although not shown in the figures, the vacuum bag is sealed to the compactor 74 and subsequently vented. The venting of the bag creates a forming force F that forces the compactor 74 against the stiffener 42. The forming force F causes the stiffener 42 to form down onto the curved tool surface 48. Autoclave treatment may be used to increase the forming force F. The outer end 90 of compactor 74 is initially engaged with the outer end 105 of stiffener 42. During this engagement, compactor 74 exerts tension 96 (fig. 15) on outer end 105 of stiffener 42 due to frictional forces between compactor 74 and stiffener 42. As compactor 74 begins to flatten as it conforms to tool surface 48, tensile strain is created in the surface of compactor 74 that contacts stiffener cover 24. This tensile strain in turn induces a tension in the stiffener cover 24 that counteracts the effect of the compressive load in the stiffener cover 24 when the stiffener cover conforms to the tool surface 48. Optionally, although not shown in the figures, a layer of high friction material or adhesive may be placed between the compactor 74 and the stiffener 42 to increase the friction between the two components and thereby increase the tension 96 applied to the stiffener 42 by the compactor 74.

The presence of the slits 82 in the cover 76 and web 80 portions of the compactor 74 allows for tensile strain and extension 92 of the compactor outer end 90 when the compactor 74 is flexed and forced down onto the curved tool surface 48. As previously mentioned, the tension 96 applied by the compactor 74 to the inboard radius 85 (fig. 9) of the stiffener 42 counteracts the compressive strain 94 in the inboard radius 85 of the stiffener 42. The reduction or elimination of compressive strain 94 in compactor 74, and therefore the reduction or elimination of compressive strain in inside radius 85 of stiffener 42, substantially reduces or eliminates ply wrinkling in cover 24 of stiffener 42 as the stiffener is formed down onto tool surface 48.

Fig. 16 shows the general steps of a method of forming a shaped composite laminate reinforcement 20. Beginning at 95, a substantially flat composite laminate charge 38 is assembled, after which, at step 97, the charge 38 is formed into a straight reinforcement 42 having a cross-section 22 of the desired shape. At 98, the curvature 30 is formed into the stiffener 42. The profile has an inboard radius 34 and an outboard radius 36. At 100, compressive strain on the medial radius 34 of the stiffener is reduced or eliminated during formation of the curvature 30 in the stiffener 42. At 102, the shaped stiffener 20 is cured, and at 104, a reduction in compressive strain on the inside radius is maintained throughout the curing of the stiffener.

FIG. 17 illustrates the general steps of a method of making a shaped composite laminate hat stiffener. Beginning at 106, a substantially flat composite laminate charge 38 is formed into a substantially straight stiffener 42 having a hat-shaped cross-section 22. At 108, compactor 44 is used to form a contour in stiffener 42. At 110, the compactor 44 is allowed to extend as it is contoured in the stiffener 42.

Embodiments of the present disclosure may be used in a variety of possible applications, particularly in the transportation industry, including, for example, aerospace, marine, automotive applications, and other applications where profiled elongate composite laminate stiffeners such as profiled stringers may be used. Thus, referring now to fig. 18 and 19, embodiments of the present disclosure may be used in the context of aircraft manufacturing and service method 114, as shown in fig. 18, and aircraft 116, as shown in fig. 19. Aircraft applications of the disclosed embodiments may include, for example, but not limited to, stringers, spars, and beams, to name a few. During pre-production, exemplary method 114 may include specification and design 18 of aircraft 116 and material procurement 120. During production, component and subassembly manufacturing 122 and system integration 124 of the aircraft occurs. Thereafter, the aircraft 116 may enter a verification and delivery process 126 to be placed in service 128. When used by a customer, the aircraft 116 is routinely maintained and serviced 130, which may also include any modifications, reconfigurations, refurbishments, and so forth.

Each of the processes of method 114 may be performed or carried out by a system integrator, a third party, and/or an operator (e.g., a consumer). For the purposes of this description, a system consumer may include, but is not limited to, any number of aircraft manufacturers and major-system subcontractors; the third party may include, but is not limited to, any number of contractors, subcontractors, and suppliers; and the operator may be an airline, leasing company, military enterprise, service organization, and so on.

As shown in FIG. 19, the aircraft 116 produced by the exemplary method 114 may include an airframe 132 with a plurality of systems 134 and an interior 136. Examples of high-level systems 134 include one or more of a propulsion system 138, an electrical system 140, a hydraulic system 142, and an environmental system 144. Any number of other systems may be included. Although an aerospace example is shown, the principles of the disclosure may be applied to other industries, such as the marine and automotive industries, among others.

The systems and methods embodied herein may be employed during any one or more of the stages of the production and service method 114. For example, components or subassemblies corresponding to the

component production processes

122 and 124 may be produced or manufactured in a manner similar to components or subassemblies produced by the aircraft 116 at the time of use 128. Furthermore, one or more apparatus embodiments, method embodiments, or a combination thereof may be utilized during

production stages

122 and 124, for example, by significantly expediting or reducing the cost of assembly of aircraft 116. Similarly, one or more of the apparatus embodiments, the method embodiments, or a combination thereof may be utilized while the aircraft 116 is in service, such as, but not limited to, maintenance and service 130.

As used herein, the phrase "at least one of," when used in relation to items in a list, means that a combination of one or more of the listed items can be used, and only one of each item in the list can be required. For example, "at least one of item a, item B, and item C" can include, but is not limited to, item a and item B, or item B. The instance can also include item a, item B, and item C or item B and item C. The item may be a specific object, thing or category. In other words, at least one means that any combination of items and items in the list can be used, but not all items in the list are required.

Thus, in summary, according to a first aspect of the invention there is provided:

A1. a method of making a shaped composite laminate reinforcement comprising:

assembling a substantially flat composite laminate charge;

forming the composite laminate charge into a substantially straight reinforcement having a desired cross-sectional shape;

forming a profile in a stiffener having an inboard radius and an outboard radius; and

the compressive strain on the medial radius is reduced during formation of the profile.

A2. There is also provided a method according to paragraph a1, wherein assembling the composite laminate charge includes laying up prepreg ply sections each having a 0 ° fiber orientation.

A3. There is also provided the method according to paragraph a2, wherein laying up the prepreg ply sections includes overlapping ply sections.

A4. There is also provided the method according to paragraph a1, wherein forming the profile in the stiffener includes:

a straight stiffener is placed onto the curved tool surface,

placing the compactor on a straight reinforcement, an

The reinforcement is pressed against the curved tool surface using a compactor.

A5. Also provided is the method according to paragraph a4, wherein reducing the compressive strain on the inboard radius includes increasing the tensile strain on the outboard radius of the compactor.

A6. There is also provided a method according to paragraph a5, wherein increasing the tensile strain on the outside radius of the compactor is performed by forming a series of slits in the outside radius of the compactor.

A7. There is also provided the method according to paragraph a4, wherein reducing the compressive strain on the inside radius of the composite laminate stiffener is performed by applying tension to the outer end of the composite laminate stiffener using a compactor.

According to another aspect of the present invention, there is provided:

B1. a method of making a shaped composite laminate hat stiffener comprising:

forming a substantially flat composite laminate charge into a substantially straight reinforcement having a hat-shaped cross-section;

forming a profile in the reinforcement using a compactor; and

the compactor is allowed to extend when it is profiled in the reinforcement.

B2. There is also provided a method according to paragraph B1, wherein:

the contour has an inside radius and an outside radius, an

Profiling with a compactor includes compacting a stiffener against a tool having a curved tool surface that substantially matches the inside radius.

B3. There is also provided the method according to paragraph B2, further comprising:

out-of-plane buckling of the stiffener in the region of the inboard radius of the stiffener is reduced by creating a tensile strain at the outboard radius that reduces the compressive strain in the region of the inboard radius of the stiffener.

B4. There is also provided a method according to paragraph B3, wherein:

creating tensile strain includes forming a series of slits in the compactor that allow an outside radius of the compactor to extend when the compactor forms the stiffener on a curved implement surface.

B5. There is also provided the method according to paragraph B3, further comprising:

curing the reinforcement, and

wherein the tensile strain continues to be developed throughout the curing of the reinforcement.

B6. There is also provided the method according to paragraph B3, wherein creating the tensile strain includes applying tension to an inside radius of the stiffener.

B7. There is also provided a method according to paragraph B6, wherein applying tension to the inside radius of the stiffener includes applying tension using a compactor, wherein the compactor is contoured and has a curvature greater than a curvature of the curved tool surface.

According to another aspect of the present invention, there is provided:

C1. an apparatus for forming a shaped composite laminate reinforcement, comprising:

a profiled compactor adapted to form and compact the composite laminate reinforcement on the tool surface, the compactor having a curvature greater than a curvature of the tool surface.

C2. There is also provided apparatus according to paragraph C1, wherein the compactor is extendable and configured to apply tension to the stiffener as the stiffener is formed on the tool surface.

C3. There is also provided apparatus according to paragraph C2, wherein:

the compactor has a hat-shaped cross-section including a cover portion, a pair of flange portions, and a pair of web portions connecting the cover portion and the flange portions, and

the cover portion includes a series of spaced apart slits therein.

C4. There is also provided apparatus according to paragraph C1, wherein:

the compactor includes an inside radius segment and an outside radius segment, and

the inboard radius segment includes a series of slits therein to allow the compactor to flex.

According to another aspect of the present invention, there is provided:

D1. an apparatus for forming a profiled composite laminate reinforcement having a hat-shaped cross-section, comprising:

a compactor adapted to form the composite laminate reinforcement onto the curved tool surface, the compactor including a cover portion, a pair of flange portions, and a pair of web portions connecting the cover and flange portions, the compactor further including a series of spaced apart slits therein extending through the flange portions and at least partially into the web portions for imparting tensile strain to the composite laminate reinforcement as the reinforcement is formed onto the curved tool surface.

D2. There is also provided the apparatus according to paragraph D1, further comprising:

a pad adapted to cover and transmit the forming force to the flange portion.

D3. There is also provided an apparatus according to paragraph D2, wherein the pad is formed from a substantially flexible material.

D4. There is also provided apparatus according to paragraph D2, wherein the bolster includes a plurality of slits therein to allow the bolster to flex and conform to the flange portion as the compactor forms the composite laminate reinforcement onto the curved tool surface.

The description of the different exemplary embodiments has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to all embodiments in the form disclosed. Many variations and modifications will be apparent to those of ordinary skill in the art. Further, different exemplary embodiments may provide different advantages over other exemplary embodiments. The embodiment was chosen and described in order to best explain the principles of the embodiments, the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various modifications as are suited to the particular use contemplated.

Claims

1. A method of making a shaped composite laminate reinforcement comprising:

assembling a substantially flat composite laminate charge;

forming a profile in the stiffener having an inboard radius and an outboard radius; and

reducing the compressive strain on the medial radius during formation of the profile,

wherein reducing compressive strain on the inboard radius comprises increasing tensile strain on the outboard radius of the compactor,

wherein increasing tensile strain on an outside radius of the compactor is performed by a change in width of a series of slits formed in the outside radius of the compactor during formation of the contour.

2. The method of claim 1, wherein assembling a composite laminate charge comprises laying up prepreg ply segments each having a 0 ° fiber orientation.

3. The method of claim 2, wherein laying up prepreg ply sections comprises overlapping the prepreg ply sections.

4. The method of claim 1, wherein forming a profile in the stiffener comprises:

placing the straight stiffener onto a curved tool surface,

placing a compactor onto the straight reinforcement, an

Compacting the stiffener onto the curved tool surface using the compactor.

5. The method of claim 4, wherein reducing the compressive strain on the medial radius of the stiffener is performed by applying tension to an outer end of the stiffener using the compactor.

6. A method of making a shaped composite laminate hat stiffener comprising:

forming a contour in the stiffener using a compactor;

allowing the compactor to extend when the compactor forms the contour in the stiffener; and

reducing out-of-plane buckling of the stiffener in the region of the inboard radius of the stiffener by creating a tensile strain at the outboard radius that reduces a compressive strain in the region of the inboard radius of the stiffener,

wherein creating tensile strain comprises varying a width of a series of slits formed in the compactor that allow an outside radius of the compactor to extend as the compactor forms the stiffener onto a curved implement surface.

7. The method of claim 6, wherein:

the profile has an inside radius and an outside radius, and

profiling with a compactor includes compacting the stiffener against a tool having a curved tool surface that substantially matches the inside radius.

8. The method of claim 6, further comprising:

curing the reinforcement and

wherein tensile strain continues to be developed throughout curing of the reinforcement.

9. The method of claim 6, wherein creating a tensile strain comprises applying tension to the inside radius of the stiffener.

10. The method of claim 9, wherein applying tension to the inside radius of the stiffener includes applying tension using the compactor, wherein the compactor is contoured and has a curvature greater than a curvature of the curved tool surface.

11. An apparatus for forming a shaped composite laminate reinforcement, comprising:

a profiled compactor adapted to form and compact the composite laminate reinforcement on the tool surface, the compactor having a curvature greater than a curvature of the tool surface,

wherein the compactor comprises an inside radius segment and an outside radius segment, and

the inboard radius section includes a series of slits in the inboard radius section that vary in width to allow the compactor to flex when forming the composite laminate stiffener.

12. The apparatus of claim 11, wherein the compactor is extendable and configured to apply tension to the stiffener as the stiffener is formed on the tool surface.

13. The apparatus of claim 12, wherein:

the cover portion includes a series of spaced apart slits in the cover portion.

14. An apparatus for forming a profiled composite laminate reinforcement having a hat-shaped cross-section, comprising:

a compactor adapted to form the composite laminate reinforcement onto a curved tool surface, the compactor including a cover portion, a pair of flange portions, and a pair of web portions connecting the cover and flange portions, the compactor further including a series of spaced apart slits in the compactor, the series of slits extending through the flange portions and at least partially into the web portions, a width of the series of slits varying as the reinforcement is formed onto the curved tool surface so as to impart a tensile strain to the composite laminate reinforcement.

15. The apparatus of claim 14, further comprising:

a pad plate adapted to cover the flange portion and transmit a forming force to the flange portion.

16. The apparatus of claim 15, wherein the pad is formed of a substantially flexible material.

17. The apparatus of claim 15, wherein the shim plate includes a plurality of slits in the shim plate that allow the shim plate to flex and conform to the flange portion as the compactor forms the composite laminate reinforcement onto the curved tool surface.